Abstract
Coal-based thermal power plants are the main source of power generation in many industrialized countries. Consequently, management of the considerable quantities of fly ash and other coal combustion residuals is of great importance with wet-storage impoundments being themost common storage option. Although the beneficial reuse of fly ash is increasing worldwide, the problems associated with diminishing impoundments capacities and possible negative impact of fly ash on environment is subsequently becoming a major concern. Legislation is proposed in the US to close or line all existing impoundments. Each of these progressions necessitates an increase in dewatering and transport of wet-disposal fly ash. Recently, geotextile tubes have been used to efficiently and economically dewater a number of low percent-solids sediments, by-products, and wastes. To investigate the effectiveness of geotextile tubes for dewatering hydraulically transported fly ash slurry a number of laboratory studies were conducted. The dewatering behavior of fly ash was evaluated with and without mixing with randomly dispersed waste fibers. The effect of anionic polyacrylamide flocculant on the dewatering performance was also evaluated. Results indicate that geotextile tubes can be effectively used for dewatering flocculated fly ash slurries, and that the strength of retained fly ash can be improved by adding fibers.